Created attachment 25269[details]
Full log
After updating to Visual Studio Professional 15.4.0, I'm uable to edit assets catalogs, and my media is missing in the application.
In the logs I found this (full log is attached)
Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogFlavoredProject|Error|0|Could not load asset catalogs
System.ArgumentException: Destination array was not long enough. Check destIndex and length, and the array's lower bounds.
at System.Array.Copy(Array sourceArray, Int32 sourceIndex, Array destinationArray, Int32 destinationIndex, Int32 length, Boolean reliable)
at System.Collections.Generic.List`1.CopyTo(T[] array, Int32 arrayIndex)
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Xamarin.VisualStudio.IOS.AssetCatalog.ItemSpecs.get_AllSpecs() in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.Interfaces\AssetCatalog\Model\ItemSpecs.cs:line 617
at Xamarin.VisualStudio.IOS.AssetCatalog.ItemSpecs.FindSpec(XCassetItem image) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.Interfaces\AssetCatalog\Model\ItemSpecs.cs:line 685
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.<>c__DisplayClass32_1.<AddDefaultItems>b__1(XCassetItem i) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 162
at System.Linq.Enumerable.Any[TSource](IEnumerable`1 source, Func`2 predicate)
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.<>c__DisplayClass32_0.<AddDefaultItems>b__0(XCassetItem x) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 162
at System.Linq.Enumerable.WhereListIterator`1.MoveNext()
at System.Linq.Enumerable.<UnionIterator>d__66`1.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.AddDefaultItems(XCasset xcasset, XCasset defaultXCasset) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 162
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.LoadCatalogs() in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 145
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogFlavoredProject.<OnAggregationComplete>b__8_0() in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\Project\AssetCatalogFlavoredProject.cs:line 57

Hi Jens,
We've already found the root cause for this issue, and we do have a patch for it.
Please let us prepare a patched version so we can share it with you and you can confirm it actually works in your case.
We'll let you know as soon as that patched version is ready.
Thanks!

Hi
We also have the issue since updating to 15.4.1 , and happens periodically during connection.
Could not load asset catalogs
Connecting to the Server...
Starting connection to 10.211.55.2...
Couldn't connect to MACSERVER Please try again.
Disconnected from the Server MACSERVER (10.211.55.2)
Visual Studio couldn't connect to MACSERVER (10.211.55.2).
This happens when we start VS Enterprise and try and load our solution and connect to our mac build host - The only remedy we have found is to shutdown our VM (W10) and our MAC and restart again.
Stack trace in Logs
_____________________
Xamarin.VisualStudio.MsBuild.ProjectBuildTracker|Error|0|Cannot start build tracking. Project is null.
Xamarin.VisualStudio.MsBuild.ProjectBuildTracker|Error|0|Cannot start build tracking. Project is null.
Xamarin.VisualStudio.MsBuild.ProjectBuildTracker|Error|0|Cannot start build tracking. Project is null.
Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogFlavoredProject|Error|0|Could not load asset catalogs
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
at System.Collections.Generic.List`1.Enumerator.MoveNext()
at System.Linq.Enumerable.WhereListIterator`1.MoveNext()
at System.Linq.Enumerable.Count[TSource](IEnumerable`1 source)
at Xamarin.VisualStudio.IOS.AssetCatalog.ItemSpecs.FindSpec(XCassetItem image) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.Interfaces\AssetCatalog\Model\ItemSpecs.cs:line 686
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.<>c__DisplayClass32_1.<AddDefaultItems>b__1(XCassetItem i) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 162
at System.Linq.Enumerable.Any[TSource](IEnumerable`1 source, Func`2 predicate)
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.<>c__DisplayClass32_0.<AddDefaultItems>b__0(XCassetItem x) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 162
at System.Linq.Enumerable.WhereListIterator`1.MoveNext()
at System.Linq.Enumerable.<UnionIterator>d__66`1.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.AddDefaultItems(XCasset xcasset, XCasset defaultXCasset) in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 162
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogManager.LoadCatalogs() in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\AssetCatalogManager.cs:line 145
at Xamarin.VisualStudio.IOS.AssetCatalog.AssetCatalogFlavoredProject.<OnAggregationComplete>b__8_0() in C:\d\lanes\5156\fe36becf\source\xamarinvs\src\Core\VisualStudio.IOS.AssetCatalog\Project\AssetCatalogFlavoredProject.cs:line 57
Xamarin.VisualStudio.Android.ContinuousPlayerDeviceProvider|Information|0|Start()
Xamarin.Messaging.Integration.State.ServerStateContext|Information|0|Connecting to the Server...